说我有琴弦
"((attr1=25 and attr2=8) or attr3=15)"
或者
"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"
或者
"(attrXYZ=10)"
甚至
"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"
以及包含字典的列表,其中每个字典在字符串中可能具有也可能没有指定的属性。Python中有没有一种简单的方法来过滤与这种类型的字符串查询匹配的字典?
我们的策略是编辑输入以使其看起来类似于Python自然理解的语法,而不是创建我们自己的解析器。这样做,我们将使用dis模块(Python字节码的Disassembler)获取字符串中的所有名称。
import dis
class Number:
def __init__(self, n, exists=True):
self.n = n
self.exists = exists
def __lt__(self, other):
return self.n < other if self.exists else False
def __le__(self, other):
return self.n <= other if self.exists else False
def __eq__(self, other):
return self.n == other if self.exists else False
def __ne__(self, other):
return self.n != other if self.exists else False
def __gt__(self, other):
return self.n > other if self.exists else False
def __ge__(self, other):
return self.n >= other if self.exists else False
def clear_entries(entry):
entry_output = entry.replace('!=', '<>').replace('=','==').replace('<>','!=')
return entry_output
def check_condition(dict_, str_):
str_ = clear_entries(str_)
for k, v in dict_.items():
exec("{0} = {1}".format(k, v))
all_names = dis.Bytecode(str_).codeobj.co_names
l_ = locals()
non_defined_names = [v for v in all_names if v not in l_]
for name in non_defined_names:
exec("{0} = Number(0, exists=False)".format(name)) # the number value does not matter here (because of the 'exists' flag)
if eval(str_):
return True
return False
if __name__ == '__main__':
entries = [
"((attr1=25 and attr2=8) or attr3=15)",
"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))",
"(2<attrXYZ<10)",
"(attr1=20 and attr2=20 and attr3=20 and attr4=20)",
"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"
]
dicts = [
{'attr1': 25, 'attr2': 8, 'attr3': 123},
{'attr1': 1, 'attr2': 8, 'attr3': 123},
{'attr1': 26, 'attr2': 8, 'attr3': 123, 'attr4': 1},
{'attr1': 1, 'attr2': 50, 'attr3': 1, 'attr4': 20},
{'attr1': -1, 'attr2': 50, 'attr3': 1, 'attr4': 20},
{'attrXYZ': 3},
{'attrXYZ': 10},
{'attr1': 20}
]
for entry in entries:
for d in dicts:
print(check_condition(d, entry), '"{0}"'.format(entry), d)
(True, '"((attr1=25 and attr2=8) or attr3=15)"', {'attr1': 25, 'attr2': 8, 'attr3': 123})
(False, '"((attr1=25 and attr2=8) or attr3=15)"', {'attr1': 1, 'attr2': 8, 'attr3': 123})
(False, '"((attr1=25 and attr2=8) or attr3=15)"', {'attr1': 26, 'attr2': 8, 'attr3': 123, 'attr4': 1})
(False, '"((attr1=25 and attr2=8) or attr3=15)"', {'attr1': 1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"((attr1=25 and attr2=8) or attr3=15)"', {'attr1': -1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"((attr1=25 and attr2=8) or attr3=15)"', {'attrXYZ': 3})
(False, '"((attr1=25 and attr2=8) or attr3=15)"', {'attrXYZ': 10})
(False, '"((attr1=25 and attr2=8) or attr3=15)"', {'attr1': 20})
(False, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attr1': 25, 'attr2': 8, 'attr3': 123})
(False, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attr1': 1, 'attr2': 8, 'attr3': 123})
(True, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attr1': 26, 'attr2': 8, 'attr3': 123, 'attr4': 1})
(False, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attr1': 1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attr1': -1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attrXYZ': 3})
(False, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attrXYZ': 10})
(False, '"((attr1>25 and attr2<50) or (attr3=10 and attr4=20))"', {'attr1': 20})
(False, '"(2<attrXYZ<10)"', {'attr1': 25, 'attr2': 8, 'attr3': 123})
(False, '"(2<attrXYZ<10)"', {'attr1': 1, 'attr2': 8, 'attr3': 123})
(False, '"(2<attrXYZ<10)"', {'attr1': 26, 'attr2': 8, 'attr3': 123, 'attr4': 1})
(False, '"(2<attrXYZ<10)"', {'attr1': 1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"(2<attrXYZ<10)"', {'attr1': -1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(True, '"(2<attrXYZ<10)"', {'attrXYZ': 3})
(False, '"(2<attrXYZ<10)"', {'attrXYZ': 10})
(False, '"(2<attrXYZ<10)"', {'attr1': 20})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attr1': 25, 'attr2': 8, 'attr3': 123})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attr1': 1, 'attr2': 8, 'attr3': 123})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attr1': 26, 'attr2': 8, 'attr3': 123, 'attr4': 1})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attr1': 1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attr1': -1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attrXYZ': 3})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attrXYZ': 10})
(False, '"(attr1=20 and attr2=20 and attr3=20 and attr4=20)"', {'attr1': 20})
(False, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attr1': 25, 'attr2': 8, 'attr3': 123})
(False, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attr1': 1, 'attr2': 8, 'attr3': 123})
(False, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attr1': 26, 'attr2': 8, 'attr3': 123, 'attr4': 1})
(False, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attr1': 1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attr1': -1, 'attr2': 50, 'attr3': 1, 'attr4': 20})
(False, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attrXYZ': 3})
(False, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attrXYZ': 10})
(True, '"(attr1=20 or (attr2=20 and attr3=20 and attr4=20 and attr1231231=1))"', {'attr1': 20})
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